I concur with most of Re-entry's post. I stopped 'cold turkey' 14 years ago after smoking 35 years (40-60 full-tar a day for the last 15). It was much more difficult than giving up alcohol completely a few months later. Medical benefits of either/both (who knows) are fantastic. I was about to lose aircrew medical (BP & ECG problems) but didn't and was able to fly a further 12 years until my retirement 2 years ago. I'm overweight because I like eating, but my BP at 64 is 120/70 and resting 60bpm. I don't cough. I don't get colds, sore throats or tonsilitis any more. I smell better.
I took up windsurfing at 60 and kiteboarding at 63.
My friend and colleague saw the benefits I was experiencing and stopped smoking, using Nicorette, a few months after me. 14 years later I believe he's on 2 packs of the gum a day, but he doesn't smoke and he smells a lot better.
rts